From owner-freebsd-hackers  Fri Sep 27 12:32:01 1996
Return-Path: owner-hackers
Received: (from root@localhost)
          by freefall.freebsd.org (8.7.5/8.7.3) id MAA27105
          for hackers-outgoing; Fri, 27 Sep 1996 12:32:01 -0700 (PDT)
Received: from gvr.win.tue.nl (root@gvr.win.tue.nl [131.155.210.19])
          by freefall.freebsd.org (8.7.5/8.7.3) with SMTP id MAA27008
          for <hackers@FreeBSD.org>; Fri, 27 Sep 1996 12:31:54 -0700 (PDT)
Received: by gvr.win.tue.nl (8.6.13/1.53)
    id VAA01983; Fri, 27 Sep 1996 21:31:40 +0200
From: guido@gvr.win.tue.nl (Guido van Rooij)
Message-Id: <199609271931.VAA01983@gvr.win.tue.nl>
Subject: Re: OPEN_MAX => which #define counts?
To: bde@zeta.org.au (Bruce Evans)
Date: Fri, 27 Sep 1996 21:31:39 +0200 (MET DST)
Cc: hackers@FreeBSD.org, mark@quickweb.com
In-Reply-To: <199609271024.UAA19546@godzilla.zeta.org.au> from Bruce Evans at "Sep 27, 96 08:24:34 pm"
X-Mailer: ELM [version 2.4ME+ PL17 (25)]
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: owner-hackers@FreeBSD.org
X-Loop: FreeBSD.org
Precedence: bulk

> No relation, except if OPEN_MAX is large (256 or so) and that many
> files are opened by several processes, then you'll quickly run out of
> system fd's.  E.g., on a 16MB system, then defaults give kern.maxfiles =
> 360, and kern.maxfilesperproc = 360.  If OPEN_MAX or the soft rlimit
> is set to 360, then one user process can eat all the system fd's, so
> root won't be able to log in.  This requires no special privileges.
> This is broken as designed.  It's easy to reduce the hard rlimit or
> kern.maxfilesperproc so that a single process can't exhaust all fd's,
> but the reasonable defaults of (CHILD_MAX = 40) and (OPEN_MAX = 64) 
> require an unreasonable number of system fd's (2560) to satisfy the
> worst case.

When I added maxfilesperproc, I made it default to maxfiles for backwards
compatibilty. But indeed the reason for adding such a thing was to be able
to at least have more control over how fd's can be spread out among
processes. The same btw for maxproc and maxprocperuid.

-Guido